So, my friend who I usually play with has the base game of Alhambra. Now we're interested in the expansions and have different options:

1) For now, buy only City Gates ~15€

2) Buy the Big Box: 50€

3) Buy the expansion set (all expansions except Falconers): 35€

4) Buy the expansion set including the base game: 40€ (would allow me to keep a copy of the base game)

My question is if there's a difference between the big box and getting just the expansions? Does the big box offer something more or better quality? I'm assuming the big box lets you keep all of it in one place and not in six different boxes, so that's definitely an advantage.

That's pretty much the advantage of the Big Box, having a nice place for everything... which of course doesn't really work when you try to put the Falconers expansion in there (unless they redid the insert). Personally I removed the insert and put each of the expansions into bags I got from Cow Cow or Art Cow or something like that. Unless you really want the "all in one" look/feel of the Big Box I would probably just purchase the expansions, or maybe the set that has the base game too if you want a second copy/want to give a copy away to someone.